Polishing jig for rolling mill backup roll bearing

ABSTRACT

A polishing jig of a hydraulic integral system is improved to increase efficiency. A polishing jig  1  for bearing for use in back-up roll of rolling mill including a shaft member  2  on which an inner ring  104  of a bearing  100  for use in back-up roll of rolling mill is fitted; and a pressure-oil chamber  12  operative in association with the feeding of a pressure oil into the shaft member  2  to protrude an outer circumferential part of the shaft member  2  radially outwardly, the polishing jig includes an inner-ring fixing portion  16  for axially fixing individual inner rings  104  of a plurality of the bearings  100  fitted on the shaft member  2  as axially arranged, wherein a plurality of the pressure-oil chambers  12  are formed internally of the shaft member  2  in correspondence to the plural bearings  100  fixed on the shaft member  2.

TECHNICAL FIELD

The present invention relates to a polishing jig for bearing for use inback-up roll of rolling mill.

BACKGROUND ART

A bearing (backing bearing) for use in back-up roll of rolling mill isin contact with a roll at its outer ring as a rotational ring and hence,the outer ring suffers fast deformation of its outside diameter surfaceor slip scars thereon, thus adversely affecting the thickness of a sheetmaterial being rolled. Accordingly, the bearing requires frequentre-polishing of the outside diameter surface of its outer ring.

As a polishing jig for the outside diameter surface of the outer ring ofthe bearing for use in back-up roll of rolling mill, there hasconventionally been known one disclosed in Japanese Examined PatentPublication No. 63-41704 (hereinafter, referred to as a prior art).

The polishing jig (re-polishing machine) of the prior art performs highaccuracy polishing of the outside diameter surface of the outer ring byrotating only the outer ring via an engagement hole formed in the outerring in a state where fit clearance/internal radial clearance of thebearing is eliminated by hydraulically protruding the polishing jigradially outwardly, the polishing jig on which an inner ring of thebearing is fitted.

However, a single conventional polishing jig can polish only one backingbearing, thus requiring much time to polish a large number of backingbearings. As a consequence, the conventional polishing jig suffers lowefficiency.

According to the conventional polishing jig, the engagement hole(carrier hole) is previously formed at an axial end face of the outerring of the bearing so as to be used to rotate the outer ring. Duringthe polishing process, a carrier tip projected from a work head of apolishing machine is engageably inserted in the engagement hole forrotating the outer ring in unison with the work head. That is, theconventional polishing jig requires the engagement hole to be formed atthe end face of the outer ring in order to rotate the outer ring. In acase where a bearing with no engagement hole formed at the end face isto be re-polished, there occurs a need to form the engagement hole,which results in low efficiency.

The present invention is directed to solution to the foregoing problemand has an object to provide a novel technical measure for achievinghigher efficiency by improving the conventional polishing jig of ahydraulic integral system as the prior art.

DISCLOSURE OF THE INVENTION

In a first aspect of the present invention, a polishing jig for bearingfor use in back-up roll of rolling mill including a shaft member onwhich an inner ring of a bearing for use in back-up roll of rolling millis fitted; and a pressure-oil chamber operative in association with thefeeding of a pressure oil into the shaft member to protrude an outercircumferential part of the shaft member radially outwardly, thepolishing jig comprises an inner-ring fixing portion for axially fixingthe individual inner rings of a plurality of the bearings fitted on theshaft member as axially arranged, wherein a plurality of thepressure-oil chambers are formed internally of the shaft member incorrespondence to the plural bearings fixed on the shaft member.

According to the first aspect of the present invention, the pluralbearings can be fitted on the shaft member as axially arranged thereonso that the individual inner rings can be fixed thereon. Furthermore,since the plural pressure-oil chambers are formed in correspondence tothe individual bearings, it is possible to apply a radially-outwardexpansion force to the corresponding inner rings of the individualbearings. Hence, outside diameter surfaces of the plural bearings can bepolished with high accuracy and efficiency.

In a second aspect of the present invention, a polishing jig for bearingfor use in back-up roll of rolling mill including a shaft member onwhich an inner ring of a bearing for use in back-up roll of rolling millis fitted and axially fixed; and a pressure-oil chamber operative inassociation with the feeding of a pressure oil into the shaft member toprotrude an outer circumferential part of the shaft member radiallyoutwardly, the polishing jig comprises an inner-ring fixing portion foraxially fixing the individual inner rings of a plurality of the bearingsfitted on the shaft member, wherein a plurality of the individuallyindependent pressure-oil chambers are formed in the shaft member incorrespondence to the plural bearings fixed on the shaft member whereasindividually independent oil paths communicated with the respectivepressure-oil chambers are formed in the shaft member whereby anarrangement for discrete adjustment of oil pressure in the individualpressure-oil chambers is established.

According to the second aspect of the present invention, the pluralityof individually independent pressure-oil chambers and oil paths areformed in correspondence to the plural bearings and hence, outsidediameter surfaces of the plural bearings can be polished with highaccuracy and efficiency. Furthermore, since the individual pressure-oilchambers are adapted for discrete adjustment of oil pressure, the amountof protrusion of the shaft member may be adjusted according toindividually varied inside diameters of the inner rings and internalradial clearances of the bearings. Thus, the individual bearings can bepolished under optimum conditions.

In a third aspect of the present invention, a polishing jig for bearingfor use in back-up roll of rolling mill including a shaft member onwhich an inner ring of a bearing for use in back-up roll of rolling millis fitted and axially fixed; and a pressure-oil chamber operative inassociation with the feeding of a pressure oil into the shaft member toprotrude an outer circumferential part of the shaft member radiallyoutwardly, the polishing jig comprises an inner-ring fixing portion foraxially fixing the individual inner rings of a plurality of the bearingsfitted on the shaft member, and an interconnection portion forinterconnecting plural outer rings thereby bringing the individual outerrings into unitary rotation.

According to the third aspect of the present invention, the pluralbearings can be fixed so as to be efficiently finished. In addition, theinterconnection portion interconnects the individual outer ring, therebyfacilitating the synchronous rotation of the outer rings of the pluralbearings.

In a fourth aspect of the present invention, the polishing jig of thearrangement of the third aspect hereof further comprises an inner-ringspacer interposed between the inner rings; and an outer-ring spacerinterposed between the outer rings as allowed to rotate relative to theinner-ring spacer via a spacer bearing. According to the fourth aspectof the present invention, it is possible to increase the rotationalaccuracies of the individual bearings, and to ensure a polishingaccuracy equal to that of polishing bearings one by one.

In a fifth aspect of the present invention, a polishing jig for anoutside diameter surface of a bearing for use in back-up roll of rollingmill including: a shaft member on which an inner ring of a bearing foruse in back-up roll of rolling mill is fitted; a pressure-oil chamberformed internally of the shaft member in a manner to be operated by apressure oil fed thereto to protrude an outer circumferential part ofthe shaft member radially outwardly; and an inner-ring fixing portionfor axially fixing the inner ring, the polishing jig comprises anouter-ring retaining portion for retaining an outer ring of the bearingas allowed to rotate in unison with the outer ring, wherein theouter-ring retaining portion includes a torque transmission portion towhich a torque for rotating the outer ring is transmitted from a torquegenerating machine for generating the torque.

According to the fifth aspect of the present invention, when the outerring is retained by the outer-ring retaining portion, the torque fromthe torque generating machine such as a polishing machine can betransmitted to the outer ring via the torque transmission portionprovided at the outer-ring retaining portion. This permits even an outerring free from an engagement hole to be rotated without forming theengagement hole thereat, thus contributing to the increased efficiency.In addition, the versatility of the polishing jig is enhanced becausethe polishing jig is capable of rotating the outer ring regardless ofthe presence of the engagement hole.

The above-mentioned outer-ring retaining portion may preferably serve tofix the outer ring axially of the shaft member. In this case, theouter-ring retaining portion is capable of axially fix even the outerring of a bearing which cannot be axially positioned without the aid ofa thrust washer. Thus, the versatility of the polishing jig is evenfurther enhanced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing a polishing jig according to a firstembodiment of the present invention;

FIG. 2 is a sectional view showing a polishing jig according to a secondembodiment hereof; and

FIG. 3 is a sectional view showing a backing bearing free from a jaw.

BEST MODES FOR CARRYING OUT THE INVENTION

FIG. 1 shows a polishing jig 1 according to a first embodiment of thepresent invention. The polishing jig 1 is used for re-polishing outsidediameter surfaces of outer rings 101 b of a plural number of(specifically, two) bearings (backing bearings) 100 for back-up roll ofrolling mill, the bearings 100 staying undisassembled or maintained asbearing assemblies when subjected to the re-polishing process.

It is noted here that the backing bearing 100 as a polishing subjectincludes an outer ring 101, an inner ring 104 and rollers 105. A sideface 101 a of the outer ring 101 is formed with an engagement hole 101 cto be engaged with a carrier projected from a work head of a polishingmachine such as a cylindrical grinder. The outer ring 101 is rotated inunison with the work head by way of engagement between the carrier andthe engagement hole 101 c.

The polishing jig 1 includes a shaft member 2 on which the inner ring104 of the bearing assembly 100 is fitted. The shaft member 2 includes ashaft 6, and a sleeve 7 attached to an outer circumference periphery ofthe shaft 6. The shaft 6 is fixedly supported between opposite centersof the polishing machine such as a cylindrical grinder. The sleeve 7 isfitted on the outer circumference of an axial center of the shaft 6. Thesleeve 7 is formed in a greater length than a combined axial length oftwo (a plural number of) backing bearings 100, such that the sleeve mayallow the two backing bearings 100 to be mounted on its outercircumference as axially arranged. An inner circumferential surface ofthe sleeve 7 is formed with recesses at two (a plural number of) axialplaces corresponding to the respective backing bearings 100 mounted onthe sleeve 7, whereby two (a plural number of) pressure-oil chambers 12,12 are formed internally of the shaft member 2. The pressure-oilchambers 12, 12 each define a space between the outer circumferentialsurface of the shaft 6 and the inner circumferential surface of thesleeve 7. The pressure-oil chambers 12, 12 are each continuous along acircumferential direction and have an axial dimension corresponding tothat of the inner ring 104 of the bearing 100 such as to be able to fixthe inner ring 104 precisely to place when supplied with a pressure oilas will be described hereinlater.

The two pressure-oil chambers 12, 12 are individually independent,whereas two (a plural number of) oil paths 13 communicated with therespective pressure-oil chambers 12, 12 are provided internally of theshaft 6. The oil paths 13 are also individually independent, thusadapted for discrete supply of the pressure oil to the respectivepressure-oil chambers 12, 12. Hence, the individual pressure-oilchambers are adapted for discrete adjustment of the hydraulic pressuretherein. Open ends of the oil paths 13, 13 are located at respectiveplaces on the outer circumferential surface of the shaft 6. These openends are each provided with a pressure-oil feed port 14 connectable witha pressure-oil feeding machine.

A space between the plural pressure-oil chambers 12, 12 is sealed withan O-ring 15 a or the like for prevention of leakage of the pressureoil. Furthermore, an O-ring 15 b for prevention of leakage of thepressure oil is disposed at a required place between the shaft 6 and thesleeve 7.

An outer jaw 16 is radially outwardly projected from one axial end ofthe sleeve 7 (the right-hand side as seen in FIG. 1), whereas an innerjaw 17 is radially inwardly projected from the other axial end of thesleeve (the left-hand side as seen in FIG. 1). A fixing ring 19 is fixedto the outer jaw 16 by means of a bolt 18. On the inner jaw 17 side, asleeve fixing nut 20 is threadedly engaged with the shaft 6, such thatthe sleeve 7 is fixed to the shaft 6 as axially positioned with respectto the shaft 6.

An inner-ring fixing nut 22 for fixing the inner ring 104 of the backingbearing 100 is provided at place axially outwardly of the sleeve fixingnut 20 (leftwardly as seen in FIG. 1). The inner-ring fixing nut 22 ismounted to the shaft 6 as threadedly engaged with a thread portion 6 aformed on the shaft 6. The nut 22 may be turned thereby to be moved onthe shaft 6 in an axial direction thereof, to be removed from the shaft6 or to fasten and fix the backing bearing 100 at place. The inner-ringfixing nut 22 is in opposing relation with the outer jaw 16 of thesleeve 7. A combination of the nut 22 and the outer jaw 16 constitute aninner-ring fixing portion which collectively clamps the inner rings 104,104 of two (the plural number of) backing bearings 100, 100 (togetherwith a spacer to be described hereinlater) from the axially oppositesides thereby axially fixing the inner rings.

A spacer is disposed between the backing bearings 100, 100 for providinga space therebetween. The spacer includes an annular inner-ring spacer25 interposed between the inner rings 104, 104; an annular outer-ringspacer 26 interposed between the outer rings 101, 101; and a bearing (asingle-row deep-groove bearing) 27 interposed between the inner-ringspacer 25 and the outer-ring spacer 26.

The outer-ring spacer 26 is allowed to rotate relative to the inner-ringspacer 25 by means of the bearing 27. The outer-ring spacer 26 includesa connector pin (interconnection portion) 30 engaged with connector-pinengagement holes 29, 29 formed in opposite side faces of the backingbearings 100, 100, the connector pin 30 interconnecting the outer rings101, 101 of the bearings such that the outer rings 101, 101 of thebearings may be rotated in unison. The interconnection of the pluralouter rings 101, 101 via the connector pin 30 is advantageous in thatall the outer rings 101 can be brought into unitary rotation simply byrotating any one of the outer rings 101. The connector-pin engagementhole 29 is located on the opposite side face from that formed with theengagement hole 101 c and circumferentially shifted 180° relative to theengagement hole 101 c, such that the outer ring 101 may not be decreasedin strength due to the formation of the engagement holes 29, 101 c.Although the description differentiates the connector-pin engagementhole 29 from the engagement hole 101 c for clarity, these engagementholes may be formed the same way. In the bearing 100, what is needed isto form the engagement holes at two places but these holes need not bedifferentiated from each other.

By virtue of the spacers 25, 26 provided between the backing bearings100, 100, the bearings 100, 100 can attain an excellent rotationaccuracy of their outer rings 101, and thereby to ensure a polishingaccuracy of a level equal to that of polishing the backing bearings 100,100 one by one.

The outer-ring spacer 26 has a smaller outside diameter than that of thebacking bearing 100 such as to obviate interference with the polishingof the outside diameter surface of the outer ring 101. The outer-ringspacer 26 is provided with a sealing member such as an O-ring 31 at itsside faces contacting the outer rings 101, 101, thereby preventing theinvasion of a polishing fluid and foreign substances.

The two backing bearings 100, 100 may be mounted to the polishing jig 1in the following manner. First, in a state where the inner-ring fixingnut 22 is removed from the shaft member 2, both the bearings 100, 100interconnected with each other as clamping the spacers 25, 26therebetween are fitted on the shaft member 2 from the left side thereofas seen in FIG. 1. Thus, one of the bearings 100, 100 is pressed againstthe outer jaw 16 at one side face of its inner ring 104. Subsequently,the inner-ring fixing nut 22 is mounted so as to clamp these bearings100, 100 whereby the bearings 100, 100 are axially fixed to place.

The polishing jig 1 with the backing bearings 100, 100 mounted thereonis mounted to the polishing machine. The pressure-oil feed ports 14, 14at the shaft 6 are each connected with respective pressure-oil feedpipes of a manually operated or automated pressure-oil feeding machine(not shown) for feeding the pressure oil to the respective pressure-oilchambers 12, 12. The pressure oil supplied to the respectivepressure-oil chambers 12, 12 causes the outer circumferential part(sleeve 7) of the shaft member 2 to protrude radially outwardly and thenthe inner rings 104 to protrude radially outwardly. The individualpressure-oil chambers 12, 12 are adjusted for elimination of radialclearance so as to ensure the high-accuracys polishing. Since thepressure-oil chambers 12, 12 can be discretely controlled in the oilpressure, it is easy to cope with the variations of the inner-ringinside diameter or of the internal radial clearance of the individualbacking bearings 100, 100.

When the polishing machine is actuated to rotate one of the outer rings101, 101 via the engagement hole 101 c while the shaft member 2 is fixedto inhibit the rotation thereof, the other outer ring 101 connected withthe former outer ring 101 via the connector pin 30 is also rotated inunison, so that the outside diameter surfaces 101 a, 101 a of the two(plural) outer rings 101, 101 can be simultaneously re-polished with anunillustrated grinding stone.

FIG. 2 illustrates a polishing jig 201 according to a second embodimentof the present invention. The polishing jig 201 is favorably used forre-polishing an outside diameter surface 301 b of an outer ring of abearing 300 for use in back-up roll of rolling mill (backing bearing) asshown in FIG. 3 without disassembling the bearing or maintaining thebearing assembly as it is. The polishing jig 201 is particularly suitedfor a bearing free from an engagement hole to engageably receive acarrier of a work head.

This bearing 300 differs from the bearing finished by the prior artdisclosed in Japanese Examined Patent Publication No. 63-41704. That is,this bearing 300 is not formed with a jaw at an inside diameter portionof its outer ring. In the case of the bearing 300 wherein an outer ring301 is free from the jaw as shown in FIG. 3, a thrust washer 303 formedfrom a resin material is interposed between a back-up saddle 302 and anend face 301 a of the outer ring 301 for the purpose of axially fixingthe outer ring 301 to place. In the case of the bearing 300 requiringthe thrust washer 303, the end face 301 a of the outer ring 301 willsustain heat cracks caused by friction with the thrust washer 303.Therefore, if the engagement hole to engageably receive the carrier ofthe work head is formed in the end face 301 a of the outer ring 301, theouter ring 301 is decreased in strength so as to be prone to failure.For this reason, the bearing 300 requiring the thrust washer 303 cannotbe formed with the engagement hole.

In a case where the bearing 300 requiring the thrust washer 303, asshown in FIG. 3, is mounted to the prior art polishing jig, it isimpossible to axially fix the outer ring 301 to place by means of thethrust washer 303. In this respect, as well, the bearing 300 isinapplicable to the prior-art polishing jig.

The polishing jig 201 according to the second embodiment is arranged asfollows in order to polish even the bearing 300 shown in FIG. 3.

Specifically, the polishing jig 201 includes a shaft member 202 on whichan inner ring 304 of the bearing assembly 300 is fitted; and a firstbearing fixing portion 203 and a second bearing fixing portion 204provided on the shaft member 202 and axially opposing each other.

The shaft member 202 includes a shaft 206, and a sleeve 207 mounted onan outer circumference of the shaft 206. The shaft 206 is fixedlysupported between opposite centers of the polishing machine such as acylindrical grinder. The sleeve 207 is fitted on the outer circumferenceof an axial center of the shaft 206. The sleeve 207 is formed with arecess at an inner circumferential surface thereof, so that apressure-oil chamber 212 is formed internally of the shaft member 202.The pressure-oil chamber 212 defines a space between the outercircumferential surface of the shaft 206 and the inner circumferentialsurface of the sleeve 207. The pressure-oil chamber 212 is continuousalong a circumferential direction and has an axial dimensioncorresponding to that of the inner ring 304 such as to be able to fixthe inner ring 304 precisely to place as supplied with the pressure oilas will be described hereinlater.

An oil path 213 for supplying the pressure oil to the pressure-oilchamber 212 is provided internally of the shaft 206. An open end of theoil path 213 is located on the outer circumferential surface of theshaft 206, and is provided with a pressure-oil feed port 214 connectableto the pressure-oil feeding machine.

An outer jaw 216 is radially outwardly projected from one axial end ofthe sleeve 207 (the right-hand side as seen in FIG. 2), whereas an innerjaw 217 is radially inwardly projected from the other axial end thereof(the left-hand side as seen in FIG. 2). A fixing ring 219 is fixed tothe outer jaw 216 by means of a bolt 218. On the inner jaw 217 side, asleeve fixing nut 220 is threadedly engaged with the shaft 206, suchthat the sleeve 207 is fixed to the shaft 206 as axially positioned withrespect to the shaft 206.

The first bearing fixing portion 203 is mounted to the shaft 206 atplace axially shifted from the sleeve 207 in one direction (theright-hand side as seen in FIG. 2). The second bearing fixing portion204 is mounted to the shaft 206 at place axially shifted from the sleevein the other direction (the left-hand side as seen in FIG. 2).

The first bearing fixing portion 203 includes a body 222 mounted to theshaft 206 via threaded engagement with a thread portion 206 a formed onthe shaft 206; and a first outer-ring fixing portion 224 carried on thebody 222 as allowed to rotate relative thereto via a bearing (conicalroller bearing) 223.

The second bearing fixing portion 204 includes a body 226 mounted to theshaft 206 via threaded engagement with a thread portion 206 b formed onthe shaft 206; and a second outer-ring fixing portion 228 carried on thebody 226 as allowed to rotate relative thereto via a bearing (conicalroller bearing) 227.

The body 226 of the second bearing fixing portion 204 axially opposesthe outer jaw 216 of the sleeve 207. A combination of the body 226 ofthe second bearing fixing portion 204 and the outer jaw 216 constitutethe inner-ring fixing portion which clamps the inner ring 304 of thebacking bearing 300 to be polished (a polishing subject) on thelaterally opposite sides thereof thereby axially fixing the inner ring304. Further, the combination of the body 226 and the outer jaw 216 alsoconstitute a roller fixing portion for axially positioning rollers 305of the backing bearing 300.

The first outer-ring fixing portion 224 and the second outer-ring fixingportion 228 axially oppose each other. A combination of these outer-ringfixing portions 224, 228 constitute an outer-ring 301 retaining portionwhich retains the outer ring 301 of the backing bearing 300 to bepolished (the polishing subject) as clamping the outer ring 301 on thelaterally opposite sides thereof and also axially fixes the outer ring301.

These outer-ring fixing portions 224, 228 constituting the outer-ringretaining portion are rotatable relative to the respective bodies 222,226 fixed to the shaft 206 and hence, the outer-ring fixing portions224, 228 are rotatable relative to the shaft 206 (the shaft member 202)as well as to the inner ring 304 fixed on the shaft member 202. Thus,the outer ring 301 and the outer-ring fixing portions 224, 228 can berotated in unison while the polishing jig 201 and the inner ring 304 areheld stationary.

The second outer-ring fixing portion 228 is formed with an engagementhole 229 to engage with a carrier projected from a work head of apolishing machine (a torque generating machine) such as a cylindricalgrinder. The engagement hole 229 serves as a torque transmission portionfor receiving a torque transmitted from the work head, so that the outerring 301 is rotated in unison with the work head. It is noted here thatthe engagement hole 229 as the torque transmission portion may bereplaced by a pin or the like.

The outer-ring fixing portions 224, 228 clamp the outer ring 301therebetween as pressed against the laterally opposite sides thereof forthe overall circumferential length thereof. Therefore, the polishingfluid and foreign substance are prevented from invading into the backingbearing 300 during the polishing process.

An oil seal 230 is provided at respective places between the body 222and the first outer-ring fixing portion 224 and between the body 226 andthe second outer-ring fixing portion 228. The first bearing fixingportion 203 and the second bearing fixing portion 204 are constructed asa grease sealed type with oil seal. Thus, the polishing jig hasexcellent internal lubricability and serviceability.

The backing bearing 300 may be mounted to the polishing jig 201 asfollows. First, in a state where the first bearing fixing portion 203and the second bearing fixing portion 204 are removed from the shaftmember 202, the backing bearing 300 is fitted on the shaft member 202from the left-hand side as seen in FIG. 2, so as to press one end faceof the inner ring 304 of the bearing against the outer jaw 216.Subsequently, the second bearing fixing portion 204 is mounted on theshaft member 202, so that the inner ring 304 is fixed as clamped betweenthe outer jaw 216 and the body 226. It is noted here that the body 226of the second bearing fixing portion 204 has its inner-ring abutmentface 226 a formed flush with an outer-ring abutment face 228 a of thesecond outer-ring fixing portion 228 and hence, the outer-ring abutmentface 228 a is also pressed against the outer ring 301. When the firstbearing fixing portion 203 is mounted to the shaft member 202 in thefinal step, the outer ring 301 is securely held by the first outer-ringfixing portion 224 and the second outer-ring fixing portion 228therebetween. The first outer-ring fixing portion 224 and the secondouter-ring fixing portion 228 have a smaller outside diameter than thatof the bearing 300 so as to obviate interference with the polishing ofthe outside diameter surface of the outer ring 301. According to theembodiment, the second bearing fixing portion 204 is a common componenthaving dual functions of fixing the inner ring and fixing the outerring, thus contributing to the reduction of the number of components andfacilitating the assembly/disassembly of the jig.

The polishing jig 201 with the backing bearing 300 mounted thereto ismounted to the polishing machine. A pressure oil pipe from the manuallyoperated or automated pressure-oil feeding machine (not shown) isconnected to the pressure-oil feed port 214 of the oil path 213 in theshaft 206 and the pressure oil is supplied to the pressure-oil chamber212. The pressure oil supplied to the pressure-oil chamber 212 causesthe outer circumferential part (sleeve 207) of the shaft member 202 toprotrude radially outwardly and then the inner ring 304 to protruderadially outwardly. The oil pressure may be properly adjusted such as toeliminate the radial clearance in the bearing 300. The high-accuracypolishing may be ensured by eliminating the radial clearance.

In addition, the polishing machine may be actuated to rotate the outerring 301 via the engagement hole 229 as the torque transmission portionwhile the shaft member 202 is securely held to prevent the rotationthereof, whereby the outside diameter surface of the outer ring 301 canbe re-polished with an unillustrated grinding stone.

According to the second embodiment, the polishing jig 201 of a hydraulicintegral system is adapted for high-accuracy re-polishing of even thebacking bearing 300 formed with no engagement hole (carrier hole) at theouter ring 301. The polishing jig 201 of the second embodiment negatesthe need for working the engagement hole and also prevents the outerring from suffering the decreased strength associated with the provisionof the engagement hole. Furthermore, the polishing jig 201 of thehydraulic integral system is also capable of highly preciselyre-polishing even the backing bearing 300 of the structure as shown inFIGS. 2 and 3 wherein the outer ring 301 cannot be axially fixed becauseof the absence of the jaw.

INDUSTRIAL APPLICABILITY

The polishing jig of the present invention may be used for efficientlypolishing the bearing for use in back-up roll of rolling mill.

1. A polishing jig for re-polishing a bearing including an inner ring,an outer ring and a roller for use in a back-up roll of a rolling millincluding a shaft member on which an inner ring of a bearing for use inthe back-up roll of the rolling mill is fitted; and a pressure-oilchamber operative in association with the feeding of pressure oil intosaid shaft member and which fixes an inner ring to a shaft member byprotruding an outer circumferential part of said shaft member radiallyoutwardly when the inner ring is fixed on the shaft member the polishingjig comprising an inner-ring fixing portion for axially fixing pluralindividual inner rings of a plurality of bearings fitted on said shaftmember as axially arranged, wherein a plurality of pressure-oil chambersare formed internally of said shaft member corresponding to theplurality of bearings fixed on said shaft member and whereinre-polishing of an outside diameter surface of the outer ring of thebearing is performed by rotating the outer ring under the conditionsthat the shaft member is fixed to prevent the shaft member fromrotating, and by polishing the outside diameter surface of the outerring.
 2. A method for polishing a bearing including an inner ring, anouter ring and a roller using the polishing jig of claim
 1. 3. Apolishing jig for re-polishing a bearing including an inner ring, anouter ring and a roller for use in a back-up roll of a rolling millincluding a shaft member on which an inner ring of a bearing for use inthe back-up roll of the rolling mill is fitted and axially fixed; and apressure-oil chamber operative in association with the feeding ofpressure oil into said shaft member and which fixes an inner ring to ashaft member by protruding an outer circumferential part of said shaftmember radially outwardly when the inner ring is fixed on the shaftmember, the polishing jig comprising an inner-ring fixing portion foraxially fixing plural individual inner rings of a plurality of saidbearings fitted on shaft member, wherein a plurality of individuallyindependent pressure-oil chambers are formed in said shaft member incorrespondence to the plurality of bearings fixed on said shaft memberwhereas individually independent oil paths communicating with therespective pressure-oil chambers are formed in said shaft member wherebyan arrangement for a discrete adjustment of oil pressure in individualpressure-oil chambers is established when the inner ring is fixed on theshaft member, and wherein re-polishing of an outside diameter surface ofthe outer ring of the bearing is performed by rotating the outer ringunder the conditions that the shaft member is fixed to prevent the shaftmember from rotating, and by polishing the outside diameter surface ofthe outer ring.
 4. A method for polishing a bearing including an innerring, an outer ring and a roller using the polishing jig of claim
 3. 5.A polishing jig for re-polishing a bearing including an inner ring, anouter ring and a roller for use in a back-up roll of a rolling millincluding a shaft member on which an inner ring of a bearing for use inthe back-up roll of the rolling mill is fitted and axially fixed; and apressure-oil chamber operative in association with the feeding ofpressure oil into said shaft member and which fixes an inner ring to ashaft member by protruding an outer circumferential part of said shaftmember radially outwardly, when the inner ring is fixed on the shaftmember, the polishing jig comprising an inner-ring fixing portion foraxially fixing individual inner rings of a plurality of bearings fittedon said shaft member, and an interconnection portion for interconnectinga plurality of outer rings thereby bringing individual outer rings intounitary rotation.
 6. A polishing jig for re-polishing a bearing for usein a back-up roll of a rolling mill as claimed in claim 5, furthercomprising an inner-ring spacer interposed between inner rings; and anouter-ring spacer interposed between the outer rings as allowed torotate relative to inner-ring spacer via a spacer bearing.
 7. A methodfor polishing a bearing including an inner ring, an outer ring and aroller using the polishing jig of claim 5.